• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

47RH OD issue?

FellowTraveler

Well-Known Member
Messages
4,757
Reaction score
6,150
Location
Nature Coast
Dodge Ram Cummins 47RH issue?

I’ve searched high and low on the web and cannot find any info on an issue that reared its ugly head today as I was cruising at 65 mph in OD & LU.

I have the OD & LU controlled by pressure valves tapped into the governor pressure port which puts out about 1psi per mile vehicle is traveling.
Anyway, the rear tires lockup and the transmission appeared to be in perhaps 2nd gear when I shut down power to the OD/LU shift solenoids the transmission went to 3rd gear while in 3rd I apply power to the OD/LU and instead of it going into OD the transmission is going to lower gear which one I have not determined but it’s not 3rd.

The 3 forward gears and reverse work fine and transmission has not over heated.

I’m stumped and hope someone can shed some light on this issue.
 
Well I ordered a stock valve body to get me going until such time as I can determine if the one in the transmission is worth a rebuild or just replaced by a high end unit.......
 
The closest info I could find in the tech manual is a overdrive overrun clutch stuck in the on position which would drag the vehicle down to a stall when OD is engaged.....being that this happened when I was doing around 65mph it may have burned the OD clutches to the point they can no longer hold perhaps why it feels like it just dropped gears when in OD now.

I'm suspecting the overdrive overrun clutch is stuck in the on position which would give this symptom however I've read when this happens reverse usually fails too but mine is working.

I have to pull the transmission and examine the overdrive unit carefully as well as the hydro governor behind it as the gov plug is known for sticking too Sonnex has a modified longer unit to eliminate that issue.

The valve body I ordered is a NOS unit that I'm going to install Sonnex zip kit into and a few other goodies.
 
Well, finally dropped the transmission pan and valve body so far valve body looks good.........however; the fluid is burnt trans and converter clutches are shot and lots of fine metal particles in the pan too. So dropping the trans and pulling overdrive unit off something tells me it all started there either the retainer clip for that 800 lb spring snapped the overdrive overrun clutch and or the governor valve took a crap.

The 47/48RE are looking real good right about now, full manual valve body maybe a good idea but I don't know how I would like constantly shifting.
 
OK, I just tried to remove the overdrive extension housing and it is stuck and I mean stuck after analyzing the OD it must be stuck on the intermediate shaft normally it just slides off easy with a little tug and slight prying with screwdriver.

Checking the case the clutches and bands are fine so the OD & converter clutches are fried from whatever happened mechanically inside the OD unit that made my wheels lock..........

I have it out about 3/8" and that's all it will go I've used wedges and a dead blow hammer to no avail.

I've searched the web for days and nothing just a video on the output shaft being stuck on the governor housing.:eek:
 
Well; finally removed the OD extension housing which is seized to the intermediate shaft everything inside the OD is toast however; upon inspecting the case and its internals nothing wrong clutches and bands are like the day I installed them.

I do need to do a thorough cleaning and reverse flush the dual trans coolers more than a few times and install a filter on the port to the trans just in case....

Going to build a full manual 47/48 hybrid now........
 

Attachments

  • DSCI0001.JPG
    DSCI0001.JPG
    49 KB · Views: 7
  • DSCI0002.JPG
    DSCI0002.JPG
    43.6 KB · Views: 6
  • DSCI0003.JPG
    DSCI0003.JPG
    58.6 KB · Views: 6
Final diagnose is that the overdrive overrun clutch failed in the "locked" position and when the wheels locked up and lucky the vehicles weight pushed through all of those ALTO clutches and premium steels in the overdrive assembly....

Now on too building this 47RH with full manual valve body and every 48RE part that fits "all six pinion planets" along with the shorter 48RE 4x4 overdrive making it a 47/48 hybrid.
 
Back
Top